Assertion level first u need to know assertions , assertions are the implied message about the economic realities of the entity which management conveys to the users through financial statements . Eg - assertions is use at the time of checking of the following ==existence , Rights and obligations , occurrence, completeness , valuation ,measurement , presentation and disclosure. And when auditor check this that's called assertion level and this time risk is arise that for example auditor after mngt. Msg say that asset is in existence but actually it is not ! that's the risk of assertion level